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{\bf Preface}
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In response to the growing interest in
building a $Neutrino$ $Factory$ to produce
high intensity beams of electron-
and muon-neutrinos and antineutrinos,
in October 1999 the Fermilab Directorate
initiated two six-month studies.
The first study, organized by N.~Holtkamp
and D.~Finley, was to investigate the
technical feasibility of an intense
neutrino source based on a muon storage
ring. This design study has produced a report
in which the basic conclusion is that
a Neutrino Factory is technically feasible,
although it requires an aggressive R\&D
program. The second study, which is the
subject of this report, was to explore
the physics potential of a Neutrino Factory
as a function of the muon beam energy and
intensity, and for oscillation physics,
the potential as a function of baseline.
The work presented in this report is the
result of the enthusiastic contributions
of many people from many institutions.
This enthusiasm made the organizers job
fun. We also want to thank our local
sub--group organizers and sub--editors
for their many effective contributions,
ranging from
running the study groups to editing the
report: Bob~Bernstein, Debbie~Harris,
Eric~Hawker, Stephen~Parke, Panagiotis~Spentzouris,
and Chris~Quigg.
Neutrino Factories seem to have caught the
imagination of the community. We hope that
this report goes some way towards documenting why.
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Steve Geer and Heidi Schellman
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